This invention relates to apparatus for comminuting solid waste materials such as plastic sheet material.
The manufacture and forming of many products from plastic produces significant amounts of plastic waste material. Applicant has previously invented several unique apparatus for comminuting severable waste material, particularly plastic sheet material, into small, rather uniform particles or pieces that can be readily recycled or disposed of in an environmentally acceptable manner. Several generations of product line have been sold by Irwin Research and Development, Inc., under the product name xe2x80x9cChesawxe2x80x9d and have gained commercial success. One such prior invention is the subject of the Irwin, et al, U.S. Pat. No. 4,687,144 granted Aug. 18, 1987. Other such prior inventions are the subject of U.S. Pat. Nos. 5,836,527; 5,860,607; and 5,893,523. However, additional improvements are needed, especially due to the use of thicker, or heavier, plastic sheet material when forming deep draw parts and further due to increases in operating speed that have been realized with motors having increased horsepower and/or torque. As a consequence, there has been found to be an increased tendency for subdivided particles to accumulate within a shear outtake manifold so as to collect and clog such manifold, which can significantly reduce operating speeds and throughput.
The first prior invention of U.S. Pat. No. 4,687,144 was a vast improvement over various types of hammermills that had previously been used. The hammermills were quite bulky, extremely noisy, and prone to substantial damage when the mill received foreign material that it could not comminute. Although such prior Irwin, et al, invention was a vast improvement and was commercially successful, particularly in view of hammermills, it was rather expensive to manufacture and sometimes noisy in operation when processing certain materials. Furthermore, it was unable to satisfactorily comminute rather high density plastic materials.
The remaining prior inventions identified above were directed to improvements over the invention of U.S. Pat. No. 4,687,144. Such improvements were directed to improving the amount of comminuted material that could be generated in a given amount of time, to improve the manner in which the comminuting apparatus operated, and/or to enhance the ability of the comminuting apparatus to efficiently subdivide pieces of material that are otherwise difficult to comminute.
As an example, U.S. Pat. No. 5,836,527 was an improvement over the invention of U.S. Pat. No. 4,687,144. More particularly, an improved comminuting apparatus is provided which can significantly increase the amount of comminuted material produced in a given amount of time. Such device is relatively less expensive to manufacture, is quieter to operate, and provides an ability to comminute a wider variety of solid waste materials. More particularly, the solid waste comminuting apparatus carries material that is severed in the device via an airstream through a fan. Subdivided pieces of material are directed via the fan to a separator screen which is mounted within a centrifugal housing. The airstream draws a relative vacuum beneath the separator screen that carries small pieces through the separator screen into an outer volute chamber for discharge from the apparatus. Large pieces which are not capable of passing through the separator screen are recycled through a recycle outlet and a recycle conduit back to scissor rolls of the device for further size reduction. However, the complexity of the apparatus and the number of parts needed to construct the apparatus increased over the device of U.S. Pat. No. 4,687,144, which has proven undesirable for certain applications.
As another example, U.S. Pat. No. 5,860,607 is directed to an apparatus for comminuting waste materials, and includes a feed roll for feeding a continuous sheet of waste material into a shear intake manifold at a desired line speed and directing the waste material to scissor rolls. An additional feature includes a screw conveyor for recirculating subdivided pieces of comminuted material. More particularly, a feed roll delivers solid waste material into overlapping scissor rolls at a desired line speed. A pneumatic conveyor, in the form of an Archimedes screw, delivers the subdivided pieces of comminuted material for sorting and reprocessing. This improvement reduced the tendency for comminuted material to collect or pile up in the shear outtake manifold. However, this improvement also increased the complexity of the comminuting apparatus, requiring the addition of a feed roll and a screw conveyor in addition to a pair of scissor rolls.
As yet another example, U.S. Pat. No. 5,893,523 is directed to an apparatus for comminuting waste material having feed roll delivery features. A feed roll is rotatably carried by a frame for directing waste material to a set of overlapping scissor rolls which shear waste material into subdivided pieces as the material passes between the scissor rolls. A separator screen is carried by the frame in association with at least one of the scissor rolls for separating subdivided pieces having a size less than a predetermined size, and for recirculating subdivided pieces having a size greater than a predetermined size. However, a separate feed roll is needed in addition to a pair of scissor rolls which complicates the machine. Furthermore, there is still a tendency for certain subdivided pieces to clog the shear outtake manifold.
The present invention provides a vastly improved comminuting apparatus that is not only able to process significantly greater amounts of material in a given time, it is also better able to recirculate and sort severed solid waste material utilizing an apparatus that is less likely to clog from subdivided pieces accumulating within the shear outtake manifold. The improved comminuting apparatus of the present invention is formed with a simplified construction having fewer moving parts, proves more reliable and less costly to manufacture, is easier to maintain and repair, and is more efficient to operate. It is also better able to sever a wider variety of different types of materials over a broader range of line speeds with increased levels of throughput of a web of material being received from a processing machine. Accordingly, the present invention provides an apparatus that is able to better move subdivided solid waste material through the comminuting apparatus without clogging in a relatively efficient and cost-effective manner, while also being able to handle a wide variety of severable materials at higher operating speeds and material feed rates.
The present invention provides a vastly improved comminuting apparatus that is also better able to sort severed solid waste material through the separator screen and withdraw such waste material from the shear outtake manifold, particularly in an apparatus having a simplified construction with fewer parts, which is less costly to manufacture, maintain and repair, and is more reliable.
A self-feeding comminuting apparatus is provided having improved pneumatic conveyor and material extraction features. According to one improvement, a pair of overlapping scissor rolls cooperate to feed waste material between the pair of scissor rolls to a recycle manifold section. The recycle manifold section delivers subdivided pieces to one of the scissor rolls to recycle the subdivided pieces for sorting and/or recirculation between the pair of scissor rolls for further subdividing. According to another feature, a pneumatic conveyor communicates with the shear outtake manifold to generate an airstream through the shear outtake manifold of sufficient velocity to entrain and remove the subdivided pieces from the shear outtake manifold where they would otherwise tend to collect and clog the manifold.
According to one aspect of the invention, a comminuting apparatus is provided having a frame, a set of overlapping scissor rolls, a shear outtake manifold, and a pneumatic conveyor. The frame has an enclosure with an entrance for receiving waste material. The set of overlapping scissor rolls is carried for co-rotation within the enclosure. The scissor rolls are operative to comminute the waste material into subdivided pieces. The shear outtake manifold is configured to collect the subdivided pieces of waste material. The pneumatic conveyor includes a source of air flow and a pneumatic duct. The pneumatic duct communicates with an upstream end of the shear outtake manifold, and is operative to deliver an airstream from the source of air flow into the shear outtake manifold. The airstream entrains the subdivided pieces and removes the subdivided pieces from the shear outtake manifold.
According to another aspect of the invention, an apparatus is provided for comminuting severable waste material into pieces. The apparatus includes a frame, a pair of overlapping scissor rolls, a shear outtake manifold, a screen and a pneumatic duct. The frame has an enclosure with an entrance opening for receiving the waste material. The pair of overlapping scissor rolls are rotatably carried by the frame. The pair of overlapping scissor rolls are operative to shear the waste material into smaller subdivided pieces as the material is passed between the scissor rolls. The shear outtake manifold is carried by the frame, and is configured to collect the subdivided pieces of waste material. The screen is carried between the scissor rolls and the shear outtake manifold. The screen is configured to permit undersized smaller pieces of a size less than the predetermined size to pass therethrough and collect in the shear outtake manifold, and to prevent oversized smaller pieces of a size greater than the predetermined size from passing therethrough. The pneumatic duct communicates with the upstream end of the shear outtake manifold. The pneumatic duct is operative to entrain and remove the undersized smaller pieces from the shear outtake manifold.
According to yet another aspect of the invention, an apparatus is provided for comminuting solid waste material. The apparatus includes a frame, a set of overlapping scissor rolls, a shear outtake manifold, a separator screen, a source of airflow, and a pneumatic duct. The frame has an enclosure with an entrance for receiving solid waste material. The set of overlapping scissor rolls are rotatably mounted within the enclosure for shearing the waste material into subdivided pieces when the material passes between the scissor rolls. The shear outtake manifold is configured to collect the subdivided pieces. The separator screen is carried by the frame between the scissor rolls and the shear outtake manifold. The separator screen has a plurality of apertures for separating subdivided pieces having a size less than a predetermined size which pass through to the shear outtake manifold for separation while preventing large subdivided pieces having a size greater than the predetermined size from passing therethrough. The source of air flow is carried by the frame and communicates with a downstream end of the shear outtake manifold. The source of airflow is operative to generate an airstream. The pneumatic duct is carried by the frame, communicates at one end with the source of air flow and at an opposite end with an upstream end of the shear outtake manifold, and is operative to provide an airstream of sufficient velocity to deliver the subdivided pieces from the shear outtake manifold through an outlet at a downstream end.
One advantage of the invention is provided in a simplified construction having a pneumatic conveyor with a pneumatic recirculation duct, or tube, that generates an airstream through the shear outtake manifold of sufficient velocity to entrain subdivided particles and remove such particles from the shear outtake manifold in order to more effectively remove the material from the comminuting apparatus and prevent clogging therein.